Conventionally, it is known that in a liquid level detecting apparatus for detecting a liquid level of a fuel tank of an automobile, in order to detecting the liquid level, the liquid level is converted into a potential difference by making contacts provided at a sliding body slide on a resistance plate with the upward and downward movement of a float moving upward and downward in accordance with the liquid level (see, for example, Patent Document 1).
In a liquid level detecting apparatus, as shown in FIG. 12, an arm 120, which is attached to a float 121, is pivotally moved in accordance with a change of the level of the liquid surface S. Contacts 111 and 112, which are provided at a sliding body 110 that moves integrally with the arm 120, slidingly contact on conductor electrodes 150A and 150B of a resistance plate 130. The liquid level is detected by detecting a voltage value that changes accordingly. In particular, in a liquid level detecting apparatus 100, the resistance plate 130 is configured by an Ag/Pd-type conductor circuit portion, which is not illustrated in the figure, sintered on an aluminum substrate. The metal contacts 111 and 112 of the sliding body 110 contact with and slide on the resistance plate 130.